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5715. Rasmussen, P.E., R.R. Allmaras, C.R. Rohde and N.C. Roager, Jr.. 1980. Crop residue influences on soil carbon and nitrogen in a wheat-fallow system.. Soil Sci. Soc. Am. J. 44(3):596-600.Seven crop residue treatments were initiated in 1931 to measure long-term residue managements effects on soil organic matter in a wheat-fallow cropping system on Pacific Northwest semiarid soils. Organic carbon and total N were measured at approximately 11-yr intervals over a 45-yr period to determine residue effects on the rate of change in soil OM content. Only the addition of 22.4 metric tons of manure/ha to straw residue before incorporating prevented a decline in soil N and C. The addition of 45 or 90 kg fertilizer N or of 22.4 metric tons of pea vines/ha to straw residue before incorporation reduced N and C loss when compared to straw only incorporation. Burning of straw in the fall following wheat harvest accelerated the loss of N, but not C. Burning of straw in the spring just prior to tillage had no effect on N or C loss.